In a previous study, it was found that the antibody response to a nonvaccine
pertussis antigen in children who were
vaccine failures was reduced compared with the response in nonvaccinated children who had
pertussis. In two acellular
pertussis vaccine efficacy trials in Sweden, we studied the convalescent-phase
enzyme-linked
immunosorbent assay (ELISA) geometric mean values (GMVs) in response to
pertussis toxin (PT), filamentous
hemagglutinin (FHA),
pertactin (PRN), and fimbriae (
FIM 2/3) in
vaccine failures and controls with
pertussis. In Germany, the antibody responses to Bordetella pertussis
antigens PT, FHA, PRN, and
FIM-2 were analyzed by ELISA according to time of serum collection after onset of illness in children with
pertussis who were
vaccine failures or who were previously unvaccinated. Antibody values were also compared by severity of clinical illness. In Sweden, infants who had received a PT
toxoid vaccine and who were
vaccine failures had a blunted response to the nonvaccine
antigen FHA compared with the response in children who had received a PT/FHA
vaccine. Similarly, infants who had
pertussis and who had received a PT/FHA
vaccine had a blunted response to the nonvaccine
antigens PRN and
FIM 2/3 compared with the response in children who were
vaccine failures and who had received a PT, FHA, PRN, and
FIM 2/3
vaccine. In Germany, in sera collected from 0 to 15 days after
pertussis illness onset, the GMVs for all 4
antigens (PT, FHA, PRN, and
FIM-2) were significantly lower in an unvaccinated group than in children who were
diphtheria-
tetanus-acellular
pertussis (
DTaP) vaccine failures. In the unvaccinated group, the GMV of the PT antibody rose rapidly over time so that it was similar to that of the
DTaP vaccine recipients at the 16- to 30-day period. In contrast, the antibody responses to FHA, PRN, and
FIM-2 at all time periods were lower in the
diphtheria-tetanus vaccine (DT) recipients than in the
DTaP vaccine failures. In both Sweden and Germany, children with less severe illness had lower antibody responses than children with typical
pertussis. Our findings indicate that upon exposure and
infection, previous vaccinees have more-robust antibody responses to the
antigens contained in the
vaccine they had received than to Bordetella
antigens that were not in the
vaccine they had received. In addition, over time the antibody responses to FHA, PRN, and
FIM-2 were greater in children with
vaccine failure (primed subjects) than in unvaccinated children (unprimed subjects) whereas the responses to PT were similar in the primed and unprimed children, as determined from sera collected after 15 days of illness. Our findings lend support to the idea that
DTaP vaccines should contain multiple
antigens.